Omron SYSMAC CJ - REFERENCE MANUAL 01-2008 Reference Manual page 646

Floating-point Math Instructions
Description
Note
Flags
Precautions
*F(456) multiplies the 32-bit floating-point number in Md+1 and Md by the 32-
bit floating-point number in Mr+1 and Mr and places the result in R+1 and R.
(The floating point data must be in IEEE754 format.)
Md+1
Mr+1
R+1
If the absolute value of the result is greater than the maximum value that can
be expressed as floating-point data, the Overflow Flag will turn ON and the
result will be output as
If the absolute value of the result is less than the minimum value that can be
expressed as floating-point data, the Underflow Flag will turn ON and the
result will be output as 0.
The various combinations of multiplicand and multiplier data will produce the
results shown in the following table.
Multiplier 0
0 0
Numeral 0
+ See note 3.
– See note 3.
NaN
1. The results could be zero (including underflows), a numeral, + , or – .
2. With CJ1H-CPU@@H-R CPU Units, an undetermined value will be output.
3. The Error Flag will be turned ON and the instruction will not be executed.
Name Label
Error Flag ER
Equals Flag =
Overflow Flag OF
Underflow Flag UF
Negative Flag N
The Multiplicand (Md+1 and Md) and Multiplier (Mr+1 and Mr) data must be in
IEEE754 floating-point data format.
Md Multiplicand (floating-point data, 32 bits)
Mr Multiplier (floating-point data, 32 bits)
Result (floating-point data, 32 bits)
R
.
Multiplicand
Numeral +
0 See note 3.
See note 1. +/–
(See note 2.)
+/– +
(See note 2.)
+/– –
(See note 2.)
Operation
ON if the multiplicand or multiplier data is not recognized
as floating-point data.
ON if the multiplicand or multiplier is not a number (NaN).
ON if + and 0 are multiplied.
ON if – and 0 are multiplied.
OFF in all other cases.
ON if both the exponent and mantissa of the result are 0.
OFF in all other cases.
ON if the absolute value of the result is too large to be
expressed as a 32-bit floating-point value.
ON if the absolute value of the result is too small to be
expressed as a 32-bit floating-point value.
ON if the result is negative.
OFF in all other cases.
Section 3-15
– NaN
See note 3.
+/–
(See note 2.)
–
+
See note 3.
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